Further, the F-4E had a significantly smaller antenna, as I mentioned. Remember that the naval phantoms were primarily interceptors, versus the bomb-truck status the F-4E had for most of its service life. Also remember that these naval interceptors would probably not have a lot in the way of AWACS/AEW support in the early '60s, and the onboard sensors become even more important. The flipside is that the naval phantoms' radar was also subject to violent landings, and the in-game similar capabilities between the J and the E are probably a simulated reflection of this difficult life for the navy birds. Now, the slatted wing birds were significantly more maneuverable, but then again they had lower top speeds. The S was probably the best in a furball, and the ability to slave the Sidewinder seeker to the HMS gave it yet another advantage.